Presence of immunoreactive glucagon in healthy and diseased human thyroid.Evidence of glucagon synthesis by this gland

Abstract

Significant amounts of immunoreactive glucagon (IRG) were determined in acid-ethanol and acid-saline extracts of human thyroid.Glucagon content of healthy thyroid, expressed as ng/g wet tissue or pg/mg protein, was significantly greater after an acid-alcohol extraction than after an acid-saline one.Furthermore IRG in acid-alcohol extracts of healthy tissue was greater than in acid alcohol extracts of diseased thyroid, while with an acid-saline procedure glucagon content was greater in the extracts of pathological tissues.No significant differences in the IRG content between calcified or follicular thyroid nodules and nodular goiter were found.Aliquots of the tissue extracts, fractionated on Bio-Gel P-030 or Sephadex G-100 columns, gave a 3,500 mol wt immunoreactive peak suggesting the existence of a polypeptide with the same size and immunological properties as pancreatic glucagon.Also, active glucagon synthesis by pieces of thyroid was established by the incorporation of L3-H-tryptophan into a 3,500 mol wt polypeptide with specific immune reaction to 30K antiserum.These results suggest that thyroid gland could represent a source of extrapancreatic glucagon in men, and therefore contribute to the circulating levels of this hormone.